WASHINGTON — Eric Holder, who served as the public face of the Obama administration's legal fight against terrorism and pushed to make the criminal justice system more even-handed, is resigning after six years on the job. He is the nation's first black attorney general.

The White House said that President Barack Obama planned to announce Holder's departure later Thursday. The White House said Holder plans to remain at the Justice Department until his successor is in place.

The 63-year-old former judge and prosecutor took office in early 2009 as the U.S. government grappled with the worst financial crisis in decades and with divisive questions on the handling of captured terrorism suspects, issues that helped shape his six-year tenure as the country's top law enforcement official. He is the fourth-longest serving attorney general in U.S. history.

He also weighed in on matters of racial fairness, taking steps to improve police relations with minorities, enforce civil rights laws and remove racial disparities in sentencing. Most recently he became the Obama administration's face in the federal response to the police shooting last month of an unarmed black 18-year-old in Ferguson, Missouri. In the shooting's aftermath, he enlisted a team of criminal justice researchers to study racial bias in law enforcement.

In his first few years on the job, Holder endured a succession of firestorms over, among other things, an ultimately-abandoned plan to try terrorism suspects in New York City, a botched gun-running probe along the Southwest border that prompted Republican calls for his resignation, and what was seen as failure to hold banks accountable for the economic meltdown.

But he stayed on after President Barack Obama won re-election, turning in his final stretch to issues that he said were personally important to him. He promoted voting rights and legal benefits for same-sex couples and pushed for changes to a criminal justice system that he said meted out punishment disproportionately to minorities.

NPR was first to report his departure.

Stung by criticism that the department hadn't been aggressive enough in targeting financial misconduct, Holder in the past year and a half secured criminal guilty pleas from two foreign banks and multi-billion-dollar civil settlements with American banks arising from the sale of toxic mortgage-backed securities during the economic meltdown. Even then, critics noted that no individuals were held accountable.

A former deputy attorney general in the Clinton administration, Holder was pulled away from private practice to reshape a Justice Department that had been tarnished by a scandal involving fired U.S. attorneys and that had authorized harsh interrogation methods for terrorism suspects.

He immediately signaled a new direction for the incoming administration by declaring that waterboarding is torture, contrary to the George W. Bush administration's insistence that it wasn't.

In the first year of his tenure, Holder was widely criticized by Republicans and some Democrats for his plan to try professed Sept. 11 mastermind Khalid Sheikh Mohammed and other alleged co-conspirators in New York. The plan was doomed by political opposition to granting civilian criminal trials to terrorist suspects, who arguably would have had greater legal protections in civilian courts than in military commissions. The attorney general gave up the effort, but je continued to maintain that civilian courts were the most appropriate venue. He argued that his original plan was vindicated by the successful prosecution in New York of Osama bin Laden's son-in-law.

Under his watch, the Justice Department cracked down on news media reporting on national security matters. The department secretly subpoenaed phone records from Associated Press reporters and editors and used a search warrant to obtain some emails of a Fox News journalist as part of a separate leak investigation.

On matters of policy, Holder spoke frankly about how his upbringing — his father emigrated from Barbados and his sister-in-law helped integrate the University of Alabama — helped shape his thinking. He even referred to America in 2010 as a "nation of cowards" in discussing matters of race. He later lamented that "systemic and unwarranted racial disparities remain disturbingly common."